Medicines such as RobitussinnDM contain acetaminaphine, I.e. Tylenol. One side effect of Tylenol over use is liver damage, i.e. sorosis. According to the tox report/autopsy, Martin had signs of liver damage. Likely caused by Sizzurp a.k.a.Lean a.k.a. Purple Drank
Cirrhosis is what you get from Tylenol. Sorosis is what you get from hanging out with George.